Study On Optimization Of Injection-Production Control Mode In Extremely Fault Block Reservoirs

A large number of fault-block reservoirs have been discovered gradually with the deepening of oilfield development.China is the country with the highest proportion of such reservoirs,more and more attention has been paid to the development of extremely complex fault block reservoirs.Due to the fragmentation and small area of fault blocks,it is difficult to form regular injection-production well patterns in extremely complex fault block reservoirs.Well patterns such as one injection-one production,one injection-two production,two injection--one production and two injection-two production are often adopted in the development.At present,there are few studies on injection-production control mode of this kind of well pattern at domestic and abroad,and most of them adopt reservoir engineering and numerical simulation methods,lack of physical simulation research on injection-production control mode for such reservoirs.According to the well pattern characteristics of extremely complex fault block reservoirs,this paper classifies and deduces the conversion relationship between reservoir prototype and physical model by using the similarity theory of water driving physical simulation,makes flat models of water driving physical simulation,designs visual physical simulation experiment schemes of injection-production control in extremely complex fault block reservoirs,the mechanism of alternating oil recovery and injection-production coupling in extremely complex fault-block reservoirs are studied,the influencing factors are analyzed and the injectionproduction control mode are optimized by combining with numerical simulation methods.The results show that the injection-production control modes such as alternating oil production and injection-production coupling change the pressure in the remaining oil detention zone,change the flow direction of underground fluid,change the fixed streamline distribution,expand the sweep volume of injected water,and thus improve the recovery of extremely complex fault block reservoirs;reservoir heterogeneity is the main internal cause affecting injection-production control of extremely complex fault block reservoirs.The production mode is optimized based on the low permeability gradient model.Oil wells in low permeability area should be opened before production together in actual development;the existence of edge water can improve the water flooding recovery degree.At the same time,the well pattern and corresponding injection-production control modes of different types of extremely complex fault block reservoirs are optimized.For fan-shaped open fault block reservoirs with 45 degrees fault angle of one injection-one production well pattern,the control mode is injection-production coupling;For fan-shaped open fault block reservoirs with 90 degrees and 135 degrees fault angle of two injection-one production well pattern,the optimal control mode is injectionproduction coupling;For closed triangular small fault-block reservoirs with one injection-two production well pattern,the optimal control mode is injection-production coupling;For closed quadrilateral small fault block reservoirs with two injection-two production well pattern,the optimal control mode is alternating oil production,forms a set of targeted injection-production control optimization technology,which provides reliable theoretical guidance for the later development and adjustment of extremely complex fault block reservoirs.